The natural product CCR5 antagonist anibamine and its analogs as anti-prostate cancer agents

Prostate cancer is a leading cause of death among males in the United States. As the chemokine receptor CCR5 is over-expressed in more aggressive forms of prostate cancer, and is also a critical receptor in inflammation, chemokine receptor CCR5 antagonists could potentially act as anti-prostate cancer agents. Anibamine, a natural product CCR5 antagonist, provides a unique molecular scaffold for the generation of novel analogs with possible anti-prostate cancer activity. A series of analogs of anibamine were designed, synthesized and tested against several prostate cancer cell lines. The analogs all acted as CCR5 antagonists at micromolar range affinity to the receptor while their anti-proliferative activity varied depending on the cell line type and their chemical structural properties. Further basal cytotoxicity characterization on these compounds indicated some of them may be suitable for in vivo studies.     

Physiology engages with functional genomics - at last

A report on the XXXV International Congress of Physiological Sciences, held together with Experimental Biology 2005, San Diego, USA, 31 March - 6 April 2005.     

Cultured vascular smooth muscle cells from porcine coronary artery possess A1 and A2 adenosine receptor activity

This study tested the hypothesis that an A1 adenosine receptor capable of inhibiting adenylate cyclase activity is present in porcine coronary vascular smooth muscle cells. In the absence of blockade of the A2 adenosine receptor, the A1 adenosine receptor agonists phenylisopropyladenosine (PIA) and cyclopentyladenosine (CPA) (10(-9) M) failed to inhibit Gpp(NH)p stimulated adenylate cyclase activity. However, after blockade of the A2 adenosine receptor with 30 nM CGS 15943A, cyclopentyladenosine (10(-9) M) inhibited Gpp(NH)p stimulated adenylate cyclase activity by 27 +/- 3% (4.3 +/- 0.7, Mean +/- SEM; pmoles/min/mg vs 5.9 +/- 0.8, P less than .05). The data demonstrate that both A1 and A2 adenosine receptors are present in coronary vascular smooth muscle. The results indicate that adenosine may mediate both vasodilation and vasoconstriction in the coronary circulation via A2 and A1 adenosine receptors, respectively.     

Humoral immune response to flagellin requires T cells and activation of innate immunity

Bacterial flagellin, the primary structural component of flagella, is a dominant target of humoral immunity upon infection by enteric pathogens and in Crohn's disease. To better understand how such responses may be regulated, we sought to define, in mice, basic mechanisms that regulate generation of flagellin-specific Igs. We observed that, in response to i.p. injection with flagellin, generation of flagellin-specific Ig required activation of innate immunity in that these responses were ablated in MyD88-deficient mice and that flagellin from Helicobacter pylori, which is known not to activate TLR5, also did not elicit Abs. Mice lacking alphabeta T cells (TCRbeta(null)) were completely deficient in their ability to make flagellin Abs in various contexts indicating that, in contrast to common belief, generation of flagellin-specific Ig is absolutely T cell dependent. In contrast to Ab responses to whole flagella (H serotyping), responses to flagellin monomers displayed only moderate serospecificity. Whereas neither oral nor rectal administration of flagellin elicited a strong serum Ab response, induction of colitis with dextran sodium sulfate resulted in a MyD88-dependent serum Ab response to endogenous flagellin, suggesting that, in an inflammatory milieu, TLR signaling promotes acquisition of Abs to intestinal flagellin. Thus, acquisition of a humoral immune response to flagellin requires activation of innate immunity, is T cell dependent, and can originate from flagellin in the intestinal tract in inflammatory conditions in the intestine.     

Measurement by electrical impedance aggregometry of porcine platelets response to selected physiological agonists

Although the domestic swine is commonly employed for physiological studies of the coronary circulation, there is relatively little data available concerning the responsiveness in whole blood of normal porcine platelets to standard physiological agonists. Such information is essential if the domestic swine is to be used as an animal model for studying potential interactions between platelets and the coronary circulation. Accordingly, the present study was undertaken to characterize the responses (aggregation and ATP release) observed in whole blood of normal porcine platelets to selected physiological agonists. The responses of platelets from 10 normal human volunteers also were studied with this system for comparison. Agents tested included ADP, arachidonic acid, collagen, epinephrine, norepinephrine, and thrombin. Studies were conducted with the Chronolog impedance aggregometer. The results demonstrate that platelets of domestic swine are reactive to ADP, arachidonic acid, and collagen. In contrast, neither epinephrine nor norepinephrine alone induced aggregation or release. Norepinephrine, however, caused modest potentiation of aggregation in response to ADP only. At 1 mM concentration each catecholamine inhibited the release response to collagen while at 10 mM each inhibited aggregation and release in response to either ADP or collagen. The data obtained indicate the domestic swine may be employed as a useful model to examine interactions between platelets and the coronary circulation.     

Dysregulation of inflammatory responses by chronic circadian disruption

Circadian rhythms modulate nearly every mammalian physiological process. Chronic disruption of circadian timing in shift work or during chronic jet lag in animal models leads to a higher risk of several pathologies. Many of these conditions in both shift workers and experimental models share the common risk factor of inflammation. In this study, we show that experimentally induced circadian disruption altered innate immune responses. Endotoxemic shock induced by LPS was magnified, leading to hypothermia and death after four consecutive weekly 6-h phase advances of the light/dark schedule, with 89% mortality compared with 21% in unshifted control mice. This may be due to a heightened release of proinflammatory cytokines in response to LPS treatment in shifted animals. Isolated peritoneal macrophages harvested from shifted mice exhibited a similarly heightened response to LPS in vitro, indicating that these cells are a target for jet lag. Sleep deprivation and stress are known to alter immune function and are potential mediators of the effects we describe. However, polysomnographic recording in mice exposed to the shifting schedule revealed no sleep loss, and stress measures were not altered in shifted mice. In contrast, we observed altered or abolished rhythms in the expression of clock genes in the central clock, liver, thymus, and peritoneal macrophages in mice after chronic jet lag. We conclude that circadian disruption, but not sleep loss or stress, are associated with jet lag-related dysregulation of the innate immune system. Such immune changes might be a common mechanism for the myriad negative health effects of shift work.